Pulp crushing apparatus

ABSTRACT

An absorbent product manufacturing apparatus including a pulp feed mechanism ( 2 ) for feeding a pulp sheet along a lower surface of a pulp guide part ( 2411 ) and a pulp crushing mechanism ( 3 ) for crushing the pulp sheet from the pulp feed mechanism ( 2 ). The pulp crushing mechanism ( 3 ) crushes the pulp sheet with a first crushing cylinder ( 312 ) and a second crushing cylinder ( 322 ). The crushing cylinders are disposed so as to be inclined with respect to a direction of feeding the pulp sheet. This reduces the force necessary to draw the pulp sheet in the feeding direction and suppresses an increase in the movement speed of the pulp sheet in crushing a rear end portion of the pulp sheet. As a result, it is possible to increase the amount of crushed pulp to be generated in a unit time and to maintain uniformity in the quality thereof.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to a pulp crushing apparatus for crushinga pulp sheet for absorbent product.

2. Description of the Related Art

In manufacturing absorbent products used for hygiene products such as adisposal diaper, conventionally, a crushing apparatus for crushing apulp sheet is used. Japanese Patent Application Laid Open Gazette No.2001-309945, for example, discloses a technique to form an absorbentlayer of an absorbent product, where a pulp sheet wound on a drum isunreeled and crushed by a crushing apparatus and the crushed pulp isblown on nonwoven fabrics to be layered. In such a crushing apparatus,for crushing pulp sheets, usually, a feed mechanism such as a feedroller feeds the pulp sheets at a constant speed to a crushing cutterwhich rotates about a rotation axis where the rotation axis is providedin parallel to the pulp sheets and it is orthogonal to a direction offeeding the pulp sheets.

In such a crushing apparatus, however, there is a possibility that apiece of pulp after passing the feed roller might be pulled by and getentangled in the crushing cutter in crushing a rear end portion of thefed pulp sheet, to go in a crushing chamber provided with the crushingcutter, without being crushed. Even if no piece of pulp gets entangled,the movement speed of pulp sheets increases with torque of the crushingcutter and this makes the amount of crushed pulp to be generated in aunit time larger than the regular amount and makes the crushed pulpcoarser. Further, since the distance between a rear end portion of apreceding pulp sheet and a following pulp sheet becomes larger for acertain interval and no crushed pulp is generated for the interval,there arises variation in the amount of crushed pulp to be generated ina unit time and quality thereof, and therefore the uniformity in qualityof an absorbent product to be formed is disadvantageously degraded.

For this reason, an operation of stopping the apparatus beforeentangling the rear end portion of the pulp sheet to remove it from thefeed roller is needed and this decreases the efficiency of crushingoperation and makes improvement in yield difficult. With two pulp feedmechanisms alternately working, a decrease in efficiency of the crushingoperation can be prevented but the apparatus disadvantageously becomeslarger.

The coarsely crushed pulp is repeatedly crushed until it becomes smallerthan a predetermined size by providing a screen with a lot of very smallopenings at an outlet of the crushing chamber for discharging thecrushed pulp and another crushing mechanism in the crushing chamber, ora full stop of generation of the crushed pulp is prevented by parallellyusing a crushing apparatus for crushing a pulp sheet coarsely andanother crushing apparatus for crushing a pulp sheet finely. Thesemethods, however, can not keep a constant amount of crushed pulp to begenerated in a unit time and thereby need measurement for the amount ofcrushed pulp before formation of an absorbent product.

SUMMARY OF THE INVENTION

The present invention is intended for a pulp crushing apparatus forcrushing a pulp sheet for absorbent product, and it is an object of thepresent invention to increase in the amount of crushed pulp to begenerated in a unit time and uniformity of quality thereof bysuppressing an increase in movement speed of a pulp sheet in crushing anear-rearend portion of the pulp sheet after passing a pulp feedmechanism.

According to the present invention, the pulp crushing apparatuscomprises a pulp feed mechanism for feeding a pulp sheet along apredetermined feed line, and a first crushing mechanism and a secondcrushing mechanism for crushing one end and the other end of the pulpsheet, respectively, with respect to a width direction of the pulpsheet, the first crushing mechanism and the second crushing mechanismbeing arranged in parallel to the width direction in the downstream ofthe pulp feed mechanism, and in the pulp crushing apparatus of thepresent invention, each of the first crushing mechanism and the secondcrushing mechanism comprises an inclined rotation axis, farther end ofwhich from a center line of the feed line is inclined toward the pulpfeed mechanism, a crushing cylinder having a substantial tubular shapewith the inclined rotation axis as a center and rotating about theinclined rotation axis to crush the pulp sheet which goes into an outerperipheral surface thereof, and a pulp support part having a substantialplate shape, for supporting the pulp sheet against rotation of the outerperipheral surface.

The pulp crushing apparatus of the present invention can increase theamount of crushed pulp to be generated in a unit time and uniformity ofquality thereof by suppressing an increase in movement speed of the pulpsheet in crushing a near-rearend portion of the pulp sheet.

According to one preferred embodiment of the present invention, therespective crushing cylinders of the first crushing mechanism and thesecond crushing mechanism are provided, being approximate to each otherand symmetrical with respect to the center line of the feed line, andthe pulp sheet is crushed in whole in the width direction thereof by thefirst crushing mechanism and the second crushing mechanism. Preferably,an angle between the inclined rotation axis of the crushing cylinder andthe center line of the feed line is not smaller than 30 degrees and notlarger than 60 degrees.

According to another preferred embodiment of the present invention, thecrushing cylinder comprises a plurality of crushing blades arrangedalong the inclined rotation axis, each of the plurality of crushingblades has a substantial disk shape orthogonal to the inclined rotationaxis, and comprises a plurality of teeth provided in its outer peripheryat a regular pitch, and teeth are arranged in a spiral fashion on theouter peripheral surface of the crushing cylinder. It is therebypossible to reduce the maximum value of a force applied to the pulpsheet by rotation of the crushing cylinder.

Preferably, the teeth of the crushing cylinder sequentially come intocontact with the pulp sheet outwards from the side of the center line ofthe feed line and teeth of the first crushing mechanism and teeth of thesecond crushing mechanism are provided symmetrically with respect to thecenter line of the feed line.

According to still another preferred embodiment of the presentinvention, a near-rearend portion of a preceding pulp sheet afterpassing the pulp feed mechanism is fed into the first crushing mechanismand the second crushing mechanism with its end pushed by a followingpulp sheet fed by the pulp feed mechanism in crushing the near-rearendportion of the preceding pulp sheet. Preferably, each of the firstcrushing mechanism and the second crushing mechanism further comprises aguide part which comes into contact with the pulp sheet while beingopposed to the pulp support part. Since the guide part is provided, itis possible to surely crush the pulp sheet even in crushing thenear-rearend portion of the pulp sheet.

According to an aspect of the present invention, the pulp crushingapparatus further comprises a control part for changing a feeding speedat which a pulp sheet is fed by the pulp feed mechanism and controllinga rotation speed of crushing cylinders of the first crushing mechanismand the second crushing mechanism on the basis of the feeding speed.With this control by the control part, it is possible to maintainuniformity in quality of the crushed pulp even if the feeding speed ofthe pulp sheet varies.

According to another aspect of the present invention, the pulp crushingapparatus further comprises a stopper provided near the center line ofthe feed line between the first crushing mechanism and the secondcrushing mechanism, being opposed to a front edge of the pulp sheet.

According to still another aspect of the present invention, the pulpcrushing apparatus further comprises a pressing part provided near thecenter line of the feed line between the first crushing mechanism andthe second crushing mechanism, for pressing a front end portion of thepulp sheet onto the pulp support part.

These and other objects, features, aspects and advantages of the presentinvention will become more apparent from the following detaileddescription of the present invention when taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view showing a construction of an absorbent productmanufacturing apparatus in accordance with a first preferred embodiment;

FIG. 2 is an enlarged front elevation showing a feed line and a pulpcrushing mechanism and their vicinity;

FIG. 3 is an enlarged plan view showing the feed line and the pulpcrushing mechanism and their vicinity;

FIG. 4 is an enlarged view showing an outer peripheral surface of asecond crushing cylinder and its vicinity;

FIG. 5 is an enlarged front elevation showing part of the feed line andthe pulp crushing mechanism in a pulp crushing apparatus in accordancewith a second preferred embodiment;

FIG. 6 is an enlarged plan view showing part of the feed line and thepulp crushing mechanism; and

FIG. 7 is a view showing another example of pulp crushing apparatus.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a view showing a construction of an absorbent productmanufacturing apparatus in accordance with the first preferredembodiment of the present invention. The absorbent product manufacturingapparatus 1 serves to manufacture an absorbent product 90 used for adisposal diaper, a sanitary napkin or the like, and the absorbentproduct 90 is manufactured by using crushed pulp which is obtained bycrushing a pulp sheet 9 which is pulp cut into a certain size.

The absorbent product manufacturing apparatus 1 comprises a pulp feedmechanism 2 for feeding the pulp sheet 9 along a predetermined feed linein the (−X) direction of FIG. 1, a pulp crushing mechanism 3 forcrushing the pulp sheet 9 fed by the pulp feed mechanism 2 downstream ofthe pulp feed mechanism 2, an absorbent product forming mechanism 4 forforming the absorbent product 90 by molding the crushed pulp generatedby the pulp crushing mechanism 3 and a control part 5 for controllingthese mechanisms. In the absorbent product manufacturing apparatus 1,the pulp feed mechanism 2 and the pulp crushing mechanism 3 serve as apulp crushing apparatus for crushing the pulp sheet 9 for absorbentproduct.

The pulp feed mechanism 2 comprises a pulp mounting part 21 on which aplurality of layered pulp sheets 9 are placed, a pulp unloadingmechanism 22 for unloading the pulp sheet 9 from the pulp mounting part21 sheet by sheet, a conveyor 23 receiving the pulp sheet 9 from thepulp unloading mechanism 22 to transfer it in the (−X) direction, and afeed line 24 provided on the (−X) side of the conveyor 23, for guidingthe pulp sheet 9 to the pulp crushing mechanism 3.

FIGS. 2 and 3 are a front elevation and a plan view, respectively,enlargedly showing the feed line 24 and the pulp crushing mechanism 3and their vicinity. For convenience of illustration, the direction ofshowing part of the pulp crushing mechanism (the second crushingmechanism 32) is changed in FIG. 2 (and FIG. 1) and the inside of partof the pulp crushing mechanism (the first crushing mechanism 31 and thesecond crushing mechanism 32) is shown in FIG. 3 (the same applies toFIGS. 5 and 7).

As shown in FIG. 2, the feed line 24 comprises an upper plate 241 and alower plate 242 each having a substantial plate shape, which are incontact with main surfaces of the pulp sheet 9 on the (+Z) and (−Z)sides, respectively. The pulp feed mechanism 2 further comprises a firstupper roller 243 provided on the (+X) side of the pulp crushingmechanism 3, a first lower roller 244 provided so as to be opposed tothe first upper roller 243 with the pulp sheet 9 interposedtherebetween, a second upper roller 245 provided on the (+X) side of thefirst upper roller 243 and a second lower roller 246 provided so as tobe opposed to the second upper roller 245 with the pulp sheet 9interposed therebetween. The first upper roller 243 and the second upperroller 245 are in contact with the main surface of the pulp sheet 9 onthe (+Z) side through openings 2410 (see FIG. 3) provided in the upperplate 241. The first lower roller 244 and the second lower roller 246are in contact with the main surface of the pulp sheet 9 on the (−Z)side through openings provided in the lower plate 242. The first upperroller 243 and the second upper roller 245 are pressed toward the lowerrollers by a pressing mechanism.

In the pulp feed mechanism 2, the first upper roller 243 and the secondupper roller 245 are rotated clockwise in FIG. 2 by motors 247 and 250through timing belts 2481 and 2482, respectively. The first lower roller244 and the second lower roller 246 are connected to the first upperroller 243 and the second upper roller 245 through gears 2491 and 2492and rotated counterclockwise in FIG. 2 with rotation of the first upperroller 243 and the second upper roller 245, and the pulp sheet 9 isthereby smoothly fed to the pulp crushing mechanism 3, being guided bythe upper plate 241 and the lower plate 242, respectively. In theabsorbent product manufacturing apparatus 1, an operation of the pulpcrushing mechanism 3 is controlled on the basis of the rotation speed ofthe motor 247 (i.e., the feeding speed of the pulp sheet 9) which iscontrolled by the control part 5 (detailed discussion on this controlwill be made later). The first lower roller 244 and the second lowerroller 246 may be passively rotated with the movement of the pulp sheet9.

The pulp crushing mechanism 3 comprises a first crushing mechanism 31and a second crushing mechanism 32 which are arranged along the widthdirection of the pulp sheet 9 (the Y direction) as shown in FIG. 3. Thefirst crushing mechanism 31 and the second crushing mechanism 32 crushportions on the (+Y) and (−Y) sides of the pulp sheet 9 on the (+Y) and(−Y) sides of the center line 91 of the feed line 24 in parallel to thedirection of feeding the pulp sheet 9 (the X direction).

The first crushing mechanism 31 comprises a first crushing cylinder 312having a substantial tubular shape with a first inclined rotation axis311 as a center and rotating about the first inclined rotation axis 311to crush the pulp sheet 9 which goes into an outer peripheral surfacethereof, and the second crushing mechanism 32 comprises a secondcrushing cylinder 322 having a substantial tubular shape with a secondinclined rotation axis 321 as a center and rotating about the secondinclined rotation axis 321 to crush the pulp sheet 9 which goes into anouter peripheral surface thereof. The first inclined rotation axis 311and the second inclined rotation axis 321 are each in parallel to thepulp sheet 9, and each farther end of the inclined rotation axes fromthe center line 91 of the feed line 24 is inclined toward the pulp feedmechanism 2, i.e., the inclined rotation axis goes toward the pulp feedmechanism 2 (the (+X) side) as become farther from the center line 91.The first inclined rotation axis 311 and the second inclined rotationaxis 321 are symmetrical with respect to the center line 91 of the feedline 24, and an angle between each of the inclined rotation axes and thecenter line 91 is not smaller than 30 degrees and not larger than 60degrees (45 degrees in this preferred embodiment). In other words, thefirst crushing cylinder 312 and the second crushing cylinder 322 areprovided so as to be inclined with respect to the direction of feedingthe pulp sheet 9.

The first crushing cylinder 312 and the second crushing cylinder 322 areprovided, being approximate to each other, symmetrically on the (+Y) and(−Y) sides of the center line 91 of the feed line 24 and are rotatedclockwise in FIG. 2 by a cylinder rotating mechanism, to crush the wholepulp sheet 9 with respect to the width direction thereof. FIGS. 1 and 2show the second crushing mechanism 32 from the direction in parallel tothe second inclined rotation axis 321 (the same applies to FIG. 5).

As shown in FIGS. 2 and 3, the second crushing cylinder 322 comprisesthirty crushing blades 33 arranged along the second inclined rotationaxis 321, and each crushing blade 33 has a substantial disk shape withthe second inclined rotation axis 321 as a center. Each blade isorthogonal to the second inclined rotation axis 321. Each crushing blade33 comprises a plurality of teeth 331 (twelve in this preferredembodiment) provided in its outer periphery at a regular pitch.Similarly, the first crushing cylinder 312 comprises thirty crushingblades 33 arranged along the first inclined rotation axis 311, and eachcrushing blade 33 has a substantial disk shape with the first inclinedrotation axis 311 as a center, orthogonal to the first inclined rotationaxis 311.

FIG. 4 is an enlarged view showing an outer peripheral surface of thesecond crushing cylinder 322 and its vicinity viewed from the directionin parallel to the second inclined rotation axis 321. As shown in FIG.4, since the thirty crushing blades 33 have the teeth 331 which are soprovided as to be shifted by one degree in the rotation direction of thesecond crushing cylinder 322 (in other words, clockwise in FIG. 4) asbecome closer to the center line 91 of the feed line 24 (see FIG. 3),tip portions of the teeth 331 are arranged in a spiral fashion with thesecond inclined rotation axis 321 as a center on the outer peripheralsurface of the second crushing cylinder 322 as shown in FIG. 3.Similarly, in the first crushing cylinder 312, tip portions of the teeth331 are arranged in a spiral fashion with the first inclined rotationaxis 311 as a center on the outer peripheral surface of the firstcrushing cylinder 312, and the teeth 331 of the first crushing cylinder312 and the teeth 331 of the second crushing cylinder 322 are providedsymmetrically on the (+Y) and (−Y) sides of the center line 91 of thefeed line 24.

In the pulp crushing mechanism 3, since the first crushing cylinder 312and the second crushing cylinder 322 are rotated synchronously through apulley 313 and a pulley 323 and the not-shown timing belts,respectively, the pulp sheet 9 is crushed sequentially by the teeth 331arranged in a spiral fashion on the outer peripheral surface of thesecrushing cylinders. Therefore, it is possible to prevent a lot of teeth331 in these crushing cylinders from coming into contact with the pulpsheet 9 at the same time and thereby reduce the maximum value of a forceapplied to the pulp sheet 9 in crushing. Since the teeth 331 of thesecrushing cylinders sequentially come into contact with the pulp sheet 9outwards from the side of the center line 91 of the feed line 24 (inother words, in the direction of becoming farther away from the centerline 91) to crush the pulp sheet 9, it is possible to prevent a force topush and bend the pulp sheet 9 toward the center line 91 and stablycrush the pulp sheet 9. Since the teeth 331 of these crushing cylinderscome into contact with the pulp sheet 9 symmetrically with respect tothe center line 91 to crush the pulp sheet 9, the force applied to thepulp sheet 9 is made symmetrical with respect to the center line 91 andit is thereby possible to prevent the pulp sheet 9 from shifting in theY direction (the direction orthogonal to the direction of feeding thepulp sheet 9).

In the absorbent product manufacturing apparatus 1, as shown in FIGS. 2and 3, front edges of the upper plate 241 and the lower plate 242 arepositioned approximately at the outer peripheral surface of the firstcrushing cylinder 312 on the (+Y) side of the center line 91 of the feedline 24 in parallel and approximately at the outer peripheral surface ofthe second crushing cylinder 322 on the (−Y) side of the center line 91in parallel. When the first crushing cylinder 312 and the secondcrushing cylinder 322 are rotated to come into contact with the pulpsheet 9 from the (+Z) side, a tip portion 2421 of the lower plate 242serves as a support part for supporting the pulp sheet 9, which goes inthese crushing cylinders from the (−Z) side, against the rotation of theouter peripheral surfaces of these crushing cylinders, and as a result,the pulp sheet 9 is surely crushed. Hereinafter, the tip portion 2421 ofthe lower plate 242 is referred to as “a pulp support part 2421”.

A tip portion 2411 of the upper plate 241, being opposed to the pulpsupport part 2421, serves as a guide part to come into contact with thepulp sheet 9 from the (+Z) side. Hereinafter, the tip portion 2411 ofthe upper plate 241 is referred to as “a pulp guide part 2411”. As thepulp support part 2421, two support parts may be providedcorrespondingly to the first crushing cylinder 312 and the secondcrushing cylinder 322, and as the pulp guide part 2411, two guide partsmay be provided correspondingly to these crushing cylinders.

When crushing of the pulp sheet 9 goes ahead and a rear end portion ofthe pulp sheet 9 (the edge on the (+X) side) passes the first upperroller 243 and the first lower roller 244 and is released from the pulpfeed mechanism 2, the pulp sheet 9 is automatically moved in the feedingdirection by a force applied to the pulp sheet 9 (a force to pull thepulp sheet 9 toward the (−X) direction) with rotation of the firstcrushing cylinder 312 and the second crushing cylinder 322.

In the pulp crushing mechanism 3, as discussed above, since the firstcrushing cylinder 312 and the second crushing cylinder 322 are providedso as to be inclined with respect to the direction of feeding the pulpsheet 9, a force applied to the pulp sheet 9 in the feeding direction(or the movement speed in the feeding direction) is a component of theforce (or the movement speed) applied to the pulp sheet 9 with rotationof these crushing cylinders in the feeding direction. As a result, it ispossible to reduce the force required to pull the pulp sheet 9 in thefeeding direction (or the movement speed) as compared with the casewhere the rotation axis of the crushing cylinder is providedorthogonally to the feeding direction, and it is further possible tosuppress an increase in movement speed of the pulp sheet 9 in crushing anear-rearend portion of the pulp sheet 9. This suppresses variation inthe amount of pulp sheet 9 to be fed to the pulp crushing mechanism 3 ina unit time also at the near-rearend portion of the pulp sheet 9, and itis thereby possible to increase the amount of crushed pulp to begenerated in a unit time and uniformity in quality thereof.

Since the pulp sheets 9 are sequentially crushed by the teeth 331arranged in a spiral fashion on the outer peripheral surfaces of thefirst crushing cylinder 312 and the second crushing cylinder 322, it ispossible to further reduce the force required to pull the pulp sheet 9in the feeding direction (in other words, prevent a large force fromdiscontinuously applying to the pulp sheet 9) and more efficientlysuppress an increase in feeding speed of the pulp sheet 9 in crushingthe near-rearend portion of the pulp sheet 9.

The movement speed of the pulp sheet 9 after passing the first upperroller 243 and the first lower roller 244 varies with the kind orthickness of the pulp sheet 9, the arrangement of the first crushingcylinder 312 and the second crushing cylinder 322 or the like. In thepulp crushing mechanism 3, by setting an angle of the first inclinedrotation axis 311 and the second inclined rotation axis 321 to thecenter line 91 to an appropriate one (45 degrees in this preferredembodiment), the movement speed of the pulp sheet 9 after passing thepulp feed mechanism 2 is made lower than the feeding speed of the pulpsheet 9 by the pulp feed mechanism 2. Therefore, in crushing anear-rearend portion of a preceding pulp sheet 9 after passing the pulpfeed mechanism 2 (exactly, the first upper roller 243 and the firstlower roller 244), the preceding pulp sheet 9 is fed into the pulpcrushing mechanism 3 with its rear end portion pushed by a followingpulp sheet 9 fed by the pulp feed mechanism 2. In other words, the rearend portion of the preceding pulp sheet 9 after passing the pulp feedmechanism 2 is fed into the pulp crushing mechanism 3 at the same speedas the one before passing the pulp feed mechanism 2 and crushed therein.As a result, the pulp sheets 9 can be always fed at a constant speed bysequentially feeding a plurality of pulp sheets 9 into the pulp crushingmechanism 3, and it is thereby possible to always maintain a uniformamount of crushed pulp to be generated in a unit time.

Since the pulp guide part 2411 and the pulp support part 2421 which comeinto contact with the pulp sheet 9 from the (+Z) and (−Z) sides areprovided closely to the outer peripheral surfaces of these crushingcylinders, even in crushing the rear end portion of the pulp sheet 9, itis possible to prevent the pulp sheet 9, which is separated from thefirst upper roller 243 and the first lower roller 244, from being drawninto the pulp crushing mechanism 3 without being crushed because of abend or the like, and each pulp sheet 9 can be surely crushedcompletely. As a result, it is possible to improve a yield of crushedpulp.

In the pulp crushing mechanism 3, as shown in FIG. 3, since the firstcrushing cylinder 312 and the second crushing cylinder 322 are providedso as to be inclined with respect to the direction of feeding the pulpsheet 9, a stopper 34 opposed to the front edge of the pulp sheet 9,which is being fed along the feed line 24 and crushed, can be providedbetween the first crushing mechanism 31 and the second crushingmechanism 32 near the center line 91 of the feed line 24. If the feedingspeed of the near-rearend portion of the pulp sheet 9 increases due tosome abnormality, the stopper 34 comes into contact with the front edgeof the pulp sheet 9 to forcedly reduce the feeding speed. As a result,even if the feeding speed of the pulp sheet 9 varies, it is possible toprevent the crushed pulp generated by the pulp crushing mechanism 3 frombecoming too fine and maintaining the uniformity in the quality of thecrushed pulp.

In the absorbent product manufacturing apparatus 1, for example, if thesupply of the pulp sheets 9 to the pulp mounting part 21 is delayed bysome cause, in order to prevent the feed of the pulp sheets 9 into thepulp crushing mechanism 3 from being stopped for a long time, thefeeding speed of the pulp sheet 9 may be made slower by reducing therotation speed of the motors 247 and 250 of the pulp feed mechanism 2.In this case, on the basis of the rotation speed of the motor 247 (inother words, the feeding speed of the pulp sheet 9), the first crushingcylinder 312 of the first crushing mechanism 31 and the second crushingcylinder 322 of the second crushing mechanism 32 are controlled by thecontrol part 5, to reduce the rotation speed of these crushingcylinders. As a result, even if the feeding speed of the pulp sheet 9varies, without stopping the operation of the absorbent productmanufacturing apparatus 1, it is possible to prevent the crushed pulpbeing generated by the pulp crushing mechanism 3 from becoming too fineand maintaining the uniformity in the quality of the crushed pulp. Ifthe feed of the pulp sheet 9 is delayed, by making the rotation speed ofthe motor 250 higher than that of the motor 247, the newly fed pulpsheet 9 can catch up with the preceding pulp sheet 9 and therefore theyield of the crushed pulp is improved.

Next, the construction of the absorbent product manufacturing apparatus1 downstream of the pulp crushing mechanism 3 will be discussed. Thecrushed pulp generated by the pulp crushing mechanism 3 is transferredto the absorbent product forming mechanism 4 through a duct 41 by ablowing mechanism (not shown) and mixed with a water-absorbent polymer(e.g., SAP (Super Absorbent Polymer)) fed by a polymer feed part 421 tobe blown on a tubular adsorption drum 42. The adsorption drum 42 isrotated clockwise in FIG. 1 and absorbs the crushed pulp and thewater-absorbent polymer with a suction mechanism (not shown) connectedto its inside onto its outer peripheral surface in which very smallvacuum holes are provided up to a predetermined level. Depending on theabsorbing power required for the absorbent product 90, mixture of thewater-absorbent polymer may be omitted.

The crushed pulp and the water-absorbent polymer absorbed on the outerperipheral surface of the adsorption drum 42 are moved toward the (−Z)side of the adsorption drum 42 by rotation of the adsorption drum 42 andthen transferred on tissue paper 92 which is unreeled from a roll 43 andconveyed by a conveyor 401 toward the (−X) direction. An adhesive (e.g.,hot melt) is applied in advance onto an upper surface of the tissuepaper 92 by an adhesive supply part 431 and the crushed pulp and thewater-absorbent polymer are bonded on the tissue paper 92 to form a pulplayer 900.

While the pulp layer 900 is transferred by the conveyor 401 toward the(−X) direction, an adhesive is applied onto one side of tissue paper 93unreeled from another roll 44 by an adhesive supply part 441 and thetissue paper 93 is bonded on the pulp layer 900 and the tissue paper 92with its one side with adhesive facing the pulp layer 900. The pulplayer 900 wrapped by the tissue paper 92 and 93 from the (−Z) and (+Z)sides, respectively, is cut into pieces 901 (hereinafter, referred to as“absorbent cores 901” since these pieces serve as core parts of theabsorbent product 90) each having a predetermined length by a cuttingpart 471 and a plurality of absorbent cores 901 are transferred by aconveyor 402 toward the (−X) direction at a predetermined pitch.

A top sheet 94 and a back sheet 95 unreeled from rolls 45 and 46, withan adhesive from adhesive supply parts 451 and 461 applied to theirrespective one side, are bonded on the tissue paper 92 and 93 wrappingthe absorbent cores 901 and cut by a cutting part 472 at a gap betweenthe adjacent absorbent cores 901, to form the absorbent product 90. Theabsorbent product 90 manufactured is unloaded from the absorbent productmanufacturing apparatus 1 by a conveyor 403.

In the absorbent product manufacturing apparatus 1, as discussed above,since the amount of crushed pulp to be generated in a unit time and itsquality can be increased by the pulp crushing mechanism 3, it ispossible to improve the uniformity in quality of the absorbent product90. If such a control is made as to reduce the feeding speed of the pulpsheet 9 and the rotation speed of the crushing cylinders, an operationspeed of the downstream constituents is controlled to decrease inproportion.

Next, a pulp crushing apparatus (a pulp feed mechanism and a pulpcrushing mechanism) in accordance with the second preferred embodimentwill be discussed. FIGS. 5 and 6 are a front elevation and a plan view,respectively, enlargedly showing part of the feed line 24 and the pulpcrushing mechanism 3 in the pulp crushing apparatus in accordance withthe second preferred embodiment. In the pulp crushing apparatus of thesecond preferred embodiment, a pulp pressing mechanism 26 serving as apressing part for pressing the front end portion of the pulp sheet 9onto the pulp support part 2421 is provided on the (−X) side of the feedline 24. Constituent elements other than the above are identical tothose shown in FIGS. 1 to 4 and are represented by the same referencesigns.

As shown in FIGS. 5 and 6, the pulp pressing mechanism 26 is providedbetween the first crushing mechanism 31 and the second crushingmechanism 32, near the center line 91 of the feed line 24 (on the centerline 91 in this preferred embodiment). The pulp pressing mechanism 26comprises a pressing member 261 having a substantial cylindrical shapeand conical ends, and the pressing member 261 is attached to a frame263, which is rotatable about a rotation axis 262. In the pulp crushingapparatus of the second preferred embodiment, a notch 2412 extendingfrom the end on the (−X) side toward the (+X) side is provided at thepulp guide part 2411 of the upper plate 241 and a tip portion of thepressing member 261 on the (−X) side is inserted into the notch 2412 ofthe pulp guide part 2411 so as to be opposed to the pulp support part2421 of the lower plate 242.

In the pulp pressing mechanism 26, torsion springs 264 are attached tothe outer periphery of the rotation axis 262 both on the (+Y) and (−Y)sides of the pressing member 261 and the frame 263, and an end portionof each torsion spring 264 protrudes from its coil part toward almostthe (+Z) direction and the other end portion protrudes toward almost the(−X) direction. The end portion protruding toward the (+Z) direction isin contact with the (−X) side of an axis 265 protruding from the frame263 toward the (+Y) and (−Y) directions and the other end portionprotruding toward the (−X) direction is in contact with the (+Z) side ofan axis 266 protruding from the pressing member 261 toward the (+Y) and(−Y) directions.

Since the torsion springs 264 are compressed in a direction where theend portion in contact with the axis 266 should approximate clockwise inFIG. 5 to the other end portion in contact with the axis 265, the axis266 is pressed down toward the (−Z) direction by the repulsion of thetorsion springs 264. As a result, a force to rotate the pressing member261 counterclockwise in FIG. 5 about the rotation axis 262 works andfront end portion of the pulp sheet 9 (the end portion on the (−X) side)is thereby pressed onto the pulp support part 2421 by the pressingmember 261 between the tip portion of the pressing member 261 on the(−X) side and the pulp support part 2421.

Two pins 267 extending in the Z direction are provided on the frame 263and a tip of the pin 267 on the (−Z) side is placed with a slight gapbetween itself and the axis 266 on the (+Z) side of the axis 266 (forexample, at a distance almost equal to the diameter of a metal wireforming the torsion spring 264). In the pulp crushing apparatus of thesecond preferred embodiment, even if the tip portion of the pressingmember 261 on the (−X) side is bounced up clockwise of FIG. 5 by theimpact applied to the pulp sheet 9 in crushing it, the movement of theaxis 266 toward the (+Z) side is controlled by the pins 267.

In the pulp crushing apparatus of the second preferred embodiment, likein the first preferred embodiment, the pulp crushing mechanism 3comprises the first crushing mechanism 31 and the second crushingmechanism 32 arranged in parallel to the width direction of the pulpsheet 9 (the Y direction), and the first crushing mechanism 31 and thesecond crushing mechanism 32 comprise the first crushing cylinder 312and the second crushing cylinder 322, respectively, for crushing thepulp sheet 9 which goes into the outer peripheral surface. The firstcrushing cylinder 312 and the second crushing cylinder 322 are provided,being approximate to each other, symmetrically on the (+Y) and (−Y)sides of the center line 91 of the feed line 24 and with rotation of thefirst crushing cylinder 312 and the second crushing cylinder 322,portions of the pulp sheet 9 on the (+Y) and (−Y) sides are crushed andthen the pulp sheet 9 is crushed in whole of the width direction.

The first inclined rotation axis 311 and the second inclined rotationaxis 321 are the respective rotation axes of the first crushing cylinder312 and the second crushing cylinder 322, and each farther end of theinclined rotation axes from the center line 91 is inclined toward thepulp feed mechanism 2. The first inclined rotation axis 311 and thesecond inclined rotation axis 321 (see FIG. 3) are symmetrical withrespect to the center line 91 of the feed line 24, and an angle betweeneach of the inclined rotation axes and the center line 91 is not smallerthan 30 degrees and not larger than 60 degrees (45 degrees in thispreferred embodiment).

In the pulp crushing apparatus of the second preferred embodiment, likein the first preferred embodiment, when crushing of the pulp sheet 9goes ahead and the rear end portion of the pulp sheet 9 (the edge on the(+X) side) passes the first upper roller 243 and the first lower roller244 in the pulp feed mechanism 2 (see FIG. 2), the pulp sheet 9 isautomatically moved in the (−X) direction by rotation of the firstcrushing cylinder 312 and the second crushing cylinder 322.

In the pulp crushing mechanism 3, like in that of the first preferredembodiment, since the first crushing cylinder 312 and the secondcrushing cylinder 322 are provided so as to be inclined with respect tothe direction of feeding the pulp sheet 9, it is possible to reduce theforce to pull the pulp sheet 9 in the feeding direction (or the movementspeed) as compared with the case where the rotation axis of the crushingcylinder is provided orthogonally to the feeding direction, and it isfurther possible to suppress an increase in movement speed of the pulpsheet 9 in crushing the near-rearend portion of the pulp sheet 9. Thissuppresses variation in the amount of pulp sheet 9 to be fed to the pulpcrushing mechanism 3 in a unit time also at the near-rearend portion ofthe pulp sheet 9, and it is thereby possible to increase the amount ofcrushed pulp to be generated in a unit time and uniformity in qualitythereof.

Like in the first preferred embodiment, since the movement speed of thepulp sheet 9 pulled by the first crushing cylinder 312 and the secondcrushing cylinder 322 is slower than the feeding speed by the pulp feedmechanism 2 (see FIG. 2), the preceding pulp sheet 9 after passing thefirst upper roller 243 and the first lower roller 244 is fed to the pulpcrushing mechanism 3 at the same speed as one before passing theserollers with its rear end portion pushed by the following pulp sheet 9and crushed therein. Therefore, the pulp sheets 9 can be always fed intothe pulp crushing mechanism 3 at a constant speed, and it is therebypossible to always maintain a uniform amount of crushed pulp to begenerated in a unit time.

Since the pulp guide part 2411 and the pulp support part 2421 which comeinto contact with the pulp sheet 9 from the (+Z) and (−Z) sides areprovided near the outer peripheral surfaces of the first crushingcylinder 312 and the second crushing cylinder 322, even in crushing thenear-rearend portion of the pulp sheet 9, it is possible to prevent thepulp sheet 9 which becomes apart from the first upper roller 243 and thefirst lower roller 244 from being drawn into the pulp crushing mechanism3 without being crushed and surely crush the pulp sheet 9 completely.

In the pulp crushing apparatus of the second preferred embodiment,especially, the pulp sheet 9 is pressed onto the pulp support part 2421by the pulp pressing mechanism 26 very near the first crushing cylinder312 and the second crushing cylinder 322 which are farthest away fromthe pulp feed mechanism 2 (in other words, portions to which thenear-rearend portion of one pulp sheet 9 is fed last). Therefore, thenear-rearend portion of the pulp sheet 9 is held between the pulppressing mechanism 26 and the pulp support part 2421 until immediatelybefore being fed into the pulp crushing mechanism 3 and it is therebypossible to surely prevent the near-rearend portion of the pulp sheet 9from being drawn into the pulp crushing mechanism 3 without beingcrushed. As a result, in the pulp crushing apparatus of the secondpreferred embodiment, it is possible to surely crush the pulp sheet 9completely.

In the pulp crushing apparatus of the second preferred embodiment, thepressing member 261 does not necessarily have to have a substantialcylindrical shape but, for example, a polygonal column-like member maybe used as the pressing member. In this case, from the viewpoint thatthe near-rearend portion of the pulp sheet 9 should be surely andcompletely pressed very near the first crushing cylinder 312 and thesecond crushing cylinder 322, it is preferable that the tip portion ofthe pressing member on the (−X) side should have a pointed shape like apolygonal pyramid.

Though the preferred embodiments of the present invention have beendiscussed above, the present invention is not limited to theabove-discussed preferred embodiments, but allows various variations.

For example, the angle between each of the first inclined rotation axis311 and the second inclined rotation axis 321 and the center line 91 maybe an appropriate one which is larger than 0 and smaller than 90 degreesin accordance with the kind and the feeding speed of the pulp sheet 9 tobe crushed, the required uniformity in quality of the crushed pulp orthe like. From the viewpoint, however, to suppress upsizing of the widthof pulp crushing mechanism 3 in the Y direction and increase the feedingspeed of the pulp sheet 9 in crushing the near-rearend portion of thepulp sheet 9, it is preferable that the angle should be not smaller than30 degrees and not larger than 60 degrees.

The first crushing cylinder 312 and the second crushing cylinder 322 donot necessarily have to be arranged symmetrically with respect to thecenter line 91 of the feed line 24 but, for example, in order to surelycrush a portion of the pulp sheet 9 near the center line 91 of the feedline 24, such an arrangement may be adopted so as to shift the positionsof these crushing cylinders in the X direction (the feeding direction)and place one (or both) of the crushing cylinders across the center line91.

In the pulp crushing mechanism 3, though the pulp sheet 9 can be stablycrushed by the first crushing cylinder 312 and the second crushingcylinder 322 provided being approximate to each other, symmetricallywith respect to the center line 91 of the feed line 24, an additionalcrushing cylinder may be provided. As shown in FIG. 7, for example, athird crushing cylinder 35 is provided between the first crushingcylinder 312 and the second crushing cylinder 322 on the center line 91of the feed line 24, to crush the whole pulp sheet 9 with respect to itswidth direction by the three crushing cylinders.

In the pulp crushing apparatus, for example, a roll-like pulp sheetwound on the drum may be unreeled and fed into the pulp crushingmechanism 3.

While the invention has been shown and described in detail, theforegoing description is in all aspects illustrative and notrestrictive. It is therefore understood that numerous modifications andvariations can be devised without departing from the scope of theinvention.

1. A pulp crushing apparatus for crushing a pulp sheet for absorbentproduct, the pulp crush apparatus comprising: a pulp feed mechanism forfeeding a pulp sheet along a predetermined feed line; and a firstcrushing mechanism and a second crushing mechanism for crushing one sideand the other side of the pulp sheet, respectively, the sides of thepulp sheet being parallel to a center line of said feed line, said firstcrushing mechanism and said second crushing mechanism being arranged inthe width direction of the pulp sheet and downstream of said pulp feedmechanism, wherein each of said first crushing mechanism and said secondcrushing mechanism comprises a crushing cylinder having a substantialtubular shape with an inclined rotation axis as a center, wherein saidcrushing cylinder is rotatable about said inclined rotation axis tocrush said pulp sheet which goes into an outer peripheral surfacethereof, said rotation axis being inclined relative to the center lineof said feeding line in a direction toward said pulp feed mechanism, anda pulp support part, having a substantial plate shape, for supportingsaid pulp sheet against rotation of said outer peripheral surface ofsaid crushing surface.
 2. The pulp crushing apparatus according to claim1, wherein said crushing cylinders of said first crushing mechanism andsaid second crushing mechanism are disposed so as to be approximatelysymmetrical to each other with respect to said center line of said feedline, and said pulp sheet is crushed in whole in said width directionthereof by said first crushing mechanism and said second crushingmechanism.
 3. The pulp crushing apparatus according to claim 1, whereinan angle between said inclined rotation axis of said crushing cylinderand said center line of said feed line is not smaller than 30 degreesand not larger than 60 degrees.
 4. The pulp crushing apparatus accordingto claim 1, wherein said crushing cylinder comprises a plurality ofcrushing blades arranged along said inclined rotation axis, each of saidplurality of crushing blades has a substantial disk shape orthogonal tosaid inclined rotation axis, and comprises a plurality of teeth providedin its outer periphery at a regular pitch, and said teeth are arrangedin a spiral fashion on said outer peripheral surface of said crushingcylinder.
 5. The pulp crushing apparatus according to claim 4, whereinsaid teeth of said crushing cylinder sequentially come into contact withsaid pulp sheet outwards from the side of said center line of said feedline.
 6. The pulp crushing apparatus according to claim 4, wherein saidteeth of said first crushing mechanism and said teeth of said secondcrushing mechanism are provided symmetrically with respect to saidcenter line of said feed line.
 7. The pulp crushing apparatus accordingto claim 1, wherein a near-rear end portion of a preceding pulp sheetafter passing said pulp feed mechanism is fed into said first crushingmechanism and said second crushing mechanism with its rear end pushed bya following pulp sheet fed by said pulp feed mechanism in crushing saidnear-rear end portion of said preceding pulp sheet.
 8. The pulp crushingapparatus according to claim 7, wherein each of said first crushingmechanism and said second crushing mechanism further comprises a guidepart which comes into contact with said pulp sheet while being opposedto said pulp support part.
 9. The pulp crushing apparatus according toclaim 1, further comprising a control part for changing a feeding speedat which a pulp sheet is fed by said pulp feed mechanism and controllinga rotation speed of crushing cylinders of said first crushing mechanismand said second crushing mechanism on the basis of said feeding speed.10. The pulp crushing apparatus according to claim 1, further comprisinga stopper provided near said center line of said feed line between saidfirst crushing mechanism and said second crushing mechanism, saidstopper being opposed to a front edge of the pulp sheet.
 11. The pulpcrushing apparatus according to claim 1, further comprising a pressingpart provided near said center line of said feed line between said firstcrushing mechanism and said second crushing mechanism, for pressing afront end portion of the pulp sheet onto said pulp support part.